diff --git a/src/controller.php b/src/controller.php
index 1cab399..570cdcd 100644
--- a/src/controller.php
+++ b/src/controller.php
@@ -100,6 +100,35 @@ class DeleteEmailController extends Controller {
     }
 }
 
+class HasNewMessagesController extends Controller {
+    private $email_ids;
+    private $address;
+    private $config_domains;
+    private $config_blocked_usernames;
+
+    public function __construct($email_ids, $address, $config_domains, array $config_blocked_usernames) {
+        $this->email_ids = $email_ids;
+        $this->address = $address;
+        $this->config_domains = $config_domains;
+        $this->config_blocked_usernames = $config_blocked_usernames;
+    }
+
+    function invoke(ImapClient $imapClient) {
+        $user = User::parseDomain($this->address, $this->config_blocked_usernames);
+        $this->validate_user($user, $this->config_domains);
+        $emails = $imapClient->get_emails($user);
+
+        $knownMailIds = explode('|', $this->email_ids);
+
+        $newMailIds = array_map(function ($mail) {
+            return $mail->id;
+        }, $emails);
+
+        $onlyNewMailIds = array_diff($newMailIds, $knownMailIds);
+        $this->viewHandler->new_mail_counter_json(count($onlyNewMailIds));
+    }
+}
+
 class RedirectToRandomAddressController extends Controller {
     private $config_domains;
 
diff --git a/src/router.php b/src/router.php
index 6896e5b..2b91c50 100644
--- a/src/router.php
+++ b/src/router.php
@@ -37,6 +37,11 @@ class Router {
             && isset($this->get_vars['address'])) {
             return new DeleteEmailController($this->get_vars['email_id'], $this->get_vars['address'], $this->config['domains'], $this->config['blocked_usernames']);
 
+        } elseif ($this->action === "has_new_messages"
+            && isset($this->get_vars['email_ids'])
+            && isset($this->get_vars['address'])) {
+            return new HasNewMessagesController($this->get_vars['email_ids'], $this->get_vars['address'], $this->config['domains'], $this->config['blocked_usernames']);
+
         } elseif ($this->action === 'random') {
             return new RedirectToRandomAddressController($this->config['domains']);
 
diff --git a/src/view.php b/src/view.php
index f1c8b2f..1219206 100644
--- a/src/view.php
+++ b/src/view.php
@@ -17,6 +17,8 @@ interface ViewHandler {
     function downloadEmailAsRfc822($full_email, $filename);
 
     function invalid_input($config_domains);
+
+    function new_mail_counter_json($counter);
 }
 
 
@@ -49,4 +51,9 @@ class ServerRenderViewHandler implements ViewHandler {
         $address = User::get_random_address($config_domains);
         $this->newAddress($address);
     }
+
+    function new_mail_counter_json($counter) {
+        header('Content-Type: application/json');
+        print json_encode($counter);
+    }
 }